Adjustable bit



(No Model.)

H, 0. DAVIS. ADJUSTABLE BIT.

No. 476,614. Patented June '7 1892.

awvewbcn wi/tvvmoco NITED STATES HENRY O. DAVIS, OF ANNISQUAM,MASSACHUSETTS.

ADJUSTABLE BIT.

SPECIFICATION forming part of Letters Patent No. 476,614, dated June *7,1892.

Application filed December 10, 1891. Serial No. 414.621- (No model.)

To all whom it may concern:

Be it known that I, HENRY O.DAv1S,a citizen of the United States ofAmerica, residing at Annisquam, in the county of Essexand State ofMassachusetts, have invented certain new and useful Improvements inAdjustable Bits; and I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame, reference being had to the accompanying drawings, and to lettersof reference marked thereon, which form a part of this specification.

This invention relates to improvements in expansible bits.

The objectof the invention is to provide a bit with an adjustable cutterwhich can be so set that the implement can be used for boring holes ofdiiterent diameters; and the invention consists in the construction andcombination of the parts, as will be hereinafter fully set forth, andparticularly pointed out in the claims.

Inthe accompanying drawings,forming part of this specification, Figure 1is a front elevation of an expansible bit constructed in accordance withmy improvement. Fig. 2 is a side elevation, partly in section. Fig. 3refers to detail views of the screw, clamping-plate, and lever detached.

A designates the shank of the bit, the lower portion of whichimmediately above the bit proper being cut away to provide a recess (1,having at its lower end an undercut shoulder a, from which extends aninclined straight surface 7), against which the lower edge of theadjustable cutter B bears. The upper end of the recess dis provided withan inclined shoulder a this construction of the lower portion of the bitas to the configuration of the recess and shoulders being substantiallythe same as that shown in Patent No. 360,090, issued to Charles E.Billings April 12, 1887, with the exception that the portion of theshank above the shoulder a is on a line with the outer end of saidshoulder.

The adjustable cutter B is constructed so as to bear against thevertical wall of the recess (L and upon the shoulders orbearing-surfaces a' and b, the upper edge Z) thereof being inclined, asshown.

C designates a clamping-plate which is provided with in wardly-inclinedupper and lower edges 0 and c, which conform to the inclina tion of theshoulder a and upper edge of the cutter, and between this plate and theshoulder a is formed a dovetailed recess, within which the adjustablecutter is clamped. Centrally this clamping-plate has a tapered aperture0 which registers with the aperture (1 in the bit, the outer end of saidaperture cl being countersunk and serrated.

D designates a screw or bolt which lies in the recess cl, the headthereof being serrated to engage with the serrations in the countersunkportion of said recess.

E designates a lever which is provided at its upper end with anoutwardly-projecting grasping portion 6, while upon its lower end isformed a conical projecting portionf, which is centrally apertured andscrew-threaded, said conical portion being adapted to enter the taperedaperture in the clamping-plate. This lever has a straight inner facewhich is adapted to bear against the straight face of the bit.

To organize the parts for use, the clampingplate, screw, and lever areproperly positioned, the lever E being placed at nearly right angleswith the shank. The screw is then turned until the serrated head thereofengages with the serrated aperture, after which the expansible bit isinserted and adjusted. The lever is then turned so as to bring it on aline with the shank, which movement will draw the head of the bolt incontact with the serrations, and at the same time the conical portion ofthe lever bearing upon the clam pin g-plate will exert a great powerupon said plate, forcing the same toward the base and against theadjustable cutter, so as to hold the same rigidly in the position it mayhave been adjusted to.

It will be obvious that by this construction there is exerted upon theadjustable cutter a force sufficient to hold the same securely inposition, and that when in use, should the parts wear, the screw can beturned to compensate for the same.

Having thus described my invention, I elaim 1. In combination with ahit, an adjustable cutter constructed substantially as shown, the bithaving a bolt-receiving aperture which is countersunK and serrated, abolt having a serrated head,'a clamping-plate having opposite beveledupper and lower edges, a conical aperture, and a lever having a conicalportion adapted to engage therewith, substantially as set forth.

2. A bit having its shank straight on one edge and cut away to receivean adjustable cutter and clamping-plate, an adjustable bolt, means forholding the same against turning, a lever pivoted upon the threadedportion of the bolt and adapted to engage with a clamping-plate, so asto force the same against the adjustable cutter, substantially as shown,and for the purpose set forth.

3. In combination with a bit constructed substantially as shown andprovided with a flat side, which is recessed, so as to provide shouldersa and (R, an adjustable cutter 13, adapted to lie partially within saidrecess, a clamping plate having oppositely beveled edges, a bolt adjustabl y secured to the bit, and a lever E, threaded for engagement withthe bolt, said lever being adapted to bear upon the clamping-plate whenturned to lie parallel with the bit, substantially as shown, and for thepurpose set forth.

4. In combination with a bit provided with an adjustable cutterand clamping-platc,whicl1 are adapted 'to be forced against each other, a boltcarried by the bit, the threaded end passing through the clamping-platefor engagement with the lever, which is pivoted thereto, said leverhaving a conical portion which is adapted to engage with the inclinedwalls of the aperture in the clamping-plate, the end of said leverextending beyond said aperture in the clamping-plate, substantially asset forth.

In testimony whereof I affix my signature in 40 presence of twowitnesses.

